Genetic Changes
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Transcript of Genetic Changes
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Genetic ChangesGene and Chromosomal Mutations
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Mutations Mutations are a result in a change in DNA
sequence › A protein with a different AA sequence could be
produced.› Germ Cell - If mutations occur in sex cells they may
be passed on to the next generation.› Somatic- A mutation occurring only in body cells may
be a problem for the individual but will not be passed on to the offspring.
Mutations may be classified as chromosomal alterations or gene mutations
› Chromosomal alterations are generally more severe because many genes are usually involved.
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Significance of Mutations• Most are neutral
• Eye color• Birth marks
• Some are harmful• Cystic Fibrosis• Down Syndrome
• Some are beneficial• Sickle Cell Anemia to Malaria• Immunity to HIV
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What Causes Mutations? There are two ways in which DNA can
become mutated:– Mutations can be inherited.
Parent to child– Mutations can be acquired.
Environmental damageMistakes when DNA is copied
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Types of Gene Mutations
Silent mutation› any mutation that is not expressed
because it does not cause a change in amino acid chain.
Point mutation › base-pair substitution› 1 base is replaced by a different
base
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• Point mutation• Only one nucleotide
changes, but it makes a different protein
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Gene Mutations Point Mutations – changes in one
or a few nucleotides– Substitution
THE FAT CAT ATE THE RAT THE FAT HAT ATE THE RAT
– Insertion THE FAT CAT ATE THE RAT THE FAT CAT XLW ATE THE
RAT– Deletion
THE FAT CAT ATE THE RAT THE FAT ATE THE RAT
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• Frameshift • Causes every codon in the DNA sequence to
be changed after the mutation:• Insertion- one or more bases are added• Deletion- one or more bases are removed
A
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Chromosomal Alterations
Deletion - part of chromosome is left out. Duplication - part of chromatid breaks
off add attaches to the sister chromatid creating a duplication of genes on the same chromosome.
› Deletion and duplication mutations are errors that occur during crossing over in Meiosis I.
Translocation - when part of one chromosome breaks off and is added to a different chromosome.
Inversion - when part of a chromosome breaks off and is reinserted backwards.
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Structural Errors
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Chromosome MutationsChanges in number and structure of
entire chromosomes Original Chromosome ABC * DEFDeletion AC * DEFDuplication ABBC * DEFTransposition ACB * DEFInversion AED * CBFTranslocation ABC * JKL
GHI * DEF
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A dinky Y chromosome and the hairy ear gene on the Y chromosome
Chromosomal Deletion